OAuth 2.0 is commonly used for authentication in web applications. It is an open standard for access delegation commonly used in authorization scenarios.

Deadlock is a phenomenon in which two or more transactions are waiting indefinitely for resources held by each other, leading to a state where none of the transactions can proceed. It is a critical issue in concurrent systems and requires careful handling to avoid system gridlock.

Infrastructure as Code helps in achieving rapid infrastructure deployment. By defining and managing infrastructure through code, deployment becomes faster, more consistent, and scalable.

"NoSQL" signifies "Not Only SQL." It represents a class of database management systems that do not strictly adhere to the traditional relational database management system principles.

The command "git reflog" displays a log of actions that have been taken in the repository. It provides a reference log, showing the history of HEAD movements, making it useful for recovering lost commits or branches.

In SQL, a JOIN combines rows from two or more tables based on a related column, while a UNION combines the results of two or more SELECT statements. JOIN operates vertically by merging rows, while UNION operates horizontally by combining result sets.

A graph is a data structure that consists of a collection of nodes and edges. Nodes represent entities, and edges represent relationships between those entities.

Evaluating the quality of a pull request involves considering code readability, maintainability, adherence to design principles, and overall code complexity. These factors contribute to a robust and maintainable codebase.

JSON (JavaScript Object Notation) is a data format commonly used for representing resources in RESTful APIs. It provides a lightweight and easy-to-read format for data exchange between the client and server.

AWS CloudFormation is the AWS service that allows users to define and provision infrastructure resources using code. It enables the creation and management of AWS resources through templates, facilitating infrastructure as code practices.